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Neither : ) You can buy a battery with built-in protection circuit and wires on the end, all pre-assembled reasonably well and partially safe (to a limited extent).
The ones without the circuit are intended for specialist use usually (such as to be assembled into a battery pack with specialist equipment).
1. So Shabaz, your saying the PCB attached to the Batt is a "Protection circuit" device ?
2. How would I discover the exact specification of the "Protection" PCB ?
3. Where would I find a Li-Ion Batt with the maH spec I want, with the correct spec "Protection circuit" PCB ?
I've looked around alot and havent seen any Li-Ion batts of 3.7v with any "Protection circuit" PCB's attached and for sale ?
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Here is an example of a Li-Ion battery that will meet your specifications. Beware, there are a lot of fake batteries and/or claims out there. Buy from a reputable seller. (Note: these are listed as Protected in the questions and answers section of the listing).
Gene, Thanks for the response.
I think you forgot to post the link or address to the batt you are recommending..
And I've see a few vids on fake batts. I agree with you there.
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You are so correct. I guess I have had a little too much exposure to paint fumes today (working on staining my new deck).
Here is the link I was referring too:
I tend to like batteries that are held in battery holders (replaceable).
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I've already got some LG 18650 3500mAH batts I wish to use, so I'm trying to positively identify the protection device needed to
attach to my batts.
Can anybody advise me on how to go about this ?
I went to the site you suggested.
The batts shown don't come with any "Holders" .
The brands are unknown to me.
2 of 2 people found this helpful
This is a specialist task done by manufacturers, for building batteries out of raw cells. They don't use a soldering iron for this, they weld the connections onto the cell. Your best bet is returning the cells (if you can), and in any case, buying cells with built-in protection (they come in the form of either either cylinder cells for battery holders, or with insulated wires [and possibly a connector] pre-attached). Some suppliers of such batteries were mentioned earlier.
The problem with your idea is I plan on building a 5 cell battery pack later on. But for now I want to start with just one cell. And I will either welding the protection/ BMS to the Batts or soldier them.
Again, my goal is learning how to identify and test the correct protection / BMS PBS for a given application.
Plus making my own cells is substantially cheaper them buying them.
So I have to learn whatever is necessary to make this happen.
Sorry but when I responded a minute ago, the technical information you included did not appear.
Where did you find that ? I'd like to investigate that further please.
Do you have a part number on the LG 18650 3500mAH batteries?
Most of the hits I found on "LG 18650 3500mAH" show the battery as 18650 LG INR18650MJ1 3500mAh High Discharge, which is an unprotected cell. A lot of high discharge batteries are unprotected, to prevent losses at the high current drains. There are several ICs that will provide protection for the batteries (combinations of over/under voltage and over current). To find that best IC, you need to understand the conditions that you will normally expect the battery to experience (maximum current draw being the most critical). If you are not using the battery for it's high discharge capacity (i.e. more for long battery life), the current becomes a little less important.
The important points with Li-Ion batteries:
- Do not over discharge the batteries. There are different ways to achieve this. This can be a part of the battery monitor, or it can be a voltage level detector that can in turn disable the battery discharge path (enable on a regulator, or control to a MOSFET).
- Monitor battery temperature during high current discharge. Do not allow the temperature to exceed the manufacturer's specification (< 75C)
- Do not over charge the battery. The charger or battery management IC can prevent overcharging.
Good luck and be very careful!
Does "IC" stand for integrated circuit ?
The Batt I'm looking at has these numbers on it: "LGEBMJ11865 Q218HO62A6" .
Max currant draw under load should be fairly low but I need to rig up a way to test for this under loaded conditions before I can provide this data.
I am using this mAH capacity size for the longer standby time and more run time under load.
I found this info about my choice of batt on the website:
Specs (Model: MJ1 in green color):
- Style: Flat Top
- Chemistry: INR
- Nominal capacity: 3500mAh
- Max Continuous Rated Discharge: 10A
- Dimensions: 65.20 mm (MAX) x 18.50 mm (MAX)
- Weight: 49.0g (Max)
- Discharge Cut-off Voltage: 2.5V
- Nominal voltage: 3.6V~3.7V
- Full Charge Voltage: 4.2V ± 0.05V
- Protected: No, Unprotected
- Standard Charge: CC/CV at 1.70A / 4.20V ± 0.05V
- Operational Charging Temperature Range: 0 to 45 degrees Celsius
- Operational Discharging Temperature Range: -20 to 60 degrees Celsius
So these specs are what I have to follow to get the right Charging / protection PCB ?
Given that you are not using the "High Discharge" aspect of the battery, this device should provide adequate protection (https://www.ebay.com/itm/1S-1A-PCB-Protection-Board-Soler-belt-for-3-7v-18650-Li-ion-lithium-Battery-Cell-/191952871950 ) They seem to have a complete line of devices (some good for up to 15A), so you should be able to find something that will work with your battery. This is a single cell solution similar to what shabaz recommended, so this will not address your multiple cell situation.
These devices all seem to have both over and under voltage protection and over current protection. The selection process, is to find a device that addresses you maximum current draw, under normal conditions, and to provide a safe margin.
Note: I have no experience with this vendor, so you need to be diligent to insure that you get what you need.
What exactly does "High Discharge" mean ?
The link you sent is a great help. You helped putting on the right path. I've been looking for these. But the size and shape is not going to be correct for this application.
I found a video that shows the round disc protection PCB like shabaz suggested.
But I still need a Battery socket or holder.
I also need to correctly identify the connector type. If I don't, then I'll have to cut the wires off my old batt, which I prefer not to.
Can you recommend a site that would possibly have a socket or holder and the correct male plug end with wires ?
The batteries that you are using can safely be discharged at 10A (which is a very significant about of energy). This is clearly in the range of 'High Discharge' rate. I once worked on a medical/cosmetic device that used a single Li-Ion cell to fire a high power laser diode. We were hitting the laser diode with bursts of 100A pulses. In order for this to work, we needed and extremely load resistive path in the battery/laser diode path (<5m Ohms), in order to keep the laser diode voltage up high enough to fire. We were therefor unable to use and in-line form of battery protection. We relied on monitoring voltage, current and temperature (of both the battery and laser diode), with multiple redundant methods in order to insure that we were safely discharging battery. In addition, we needed to perform tests, to prove that even in the event of a direct short circuit (with our protection circuits/overrides disabled), that the device would not explode. It did smoke like crazy and was completely destroyed (case melted and PCB heavily charred), but no explosion.
One interesting thought is to mount the protection circuit on the backside of a battery holder and connect the outputs (protected) of the circuit to your PCB. There may even be some protection devices from that ebay supplier that are built like that.
Farnell 2673609 will do you, its a Keystone 1043P, Farnell have no stock at the moment but you
can get them from Mouser who have > 6000 of them.
There are other versions with different contacts.
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I also agree with Gene, that's the best advice possible, get it from a reputable source, and they will state if the battery is protected or not (either on the web page or the datasheet).
Often the ones with wires attached will have the protection circuit built-in, but the seller will specify it.
If you're not buying a battery to fit a holder then for your safety it ought to be a battery with wires attached, not those foil tabs.
Farnell/Newark has some, and TME.eu has quite a large battery range, and Farnell/Newark and TME.eu are in the group of reputable sellers.
The photo attached is of a 3.7v 870mAH Lipo battery. It has a circuit protection PCB (of some kind) attached to it.
My goal is to replace this Batt with a Li Ion Batt of the same Voltage but with 3000 mAH of currant.
So my question is: Should I remove this protection device and add it to the Li Ion Batt, or should or could I
calculate or obtain a new protection device (some how) for the larger mAH battery ?
Do I sound like I'm uneducated in the field of electronic ? You'd be right. But I do have some electrical experiencs
and I can soldier.
Any video explaining this lesson would be greatly appreciated.